So there is not a ton of data on this subject as to automobile affects, specifically. The key here is shielding for critical components. Most folks think of computers and such, and also transmission lines/grids. Large grids and long wires have the most vulnerability because the pulse interacts with them over a large area creating a HUGE power spike. In a car the most likely damaged items will be smaller wires such as micro-circuits (electronics) and longer wires such as coils. While the book you refer takes considerable artistic license with the running of old cars, in theory they would be the easiest to repair and much less dependent on modern electronics, but still vulnerable to EMP. Aside of the electronics: batteries, ignition coil, alternator, starter motor and fuses would all be very subject. Other ignition system components should be OK if you are not too close to the blast. For this to be doable, I would suggest that all component of an ignition system, full set of fuses be stored. Additionally, anything that resembles a coil, alternator, relay, starter motor be stored in a grounded metal box.
Thanks for your post.